Empty coupe, next to Fiat, an azure colour (8)
I believe the answer is:
cerulean
'azure colour' is the definition.
(shade of blue)
'empty coupe next to fiat an' is the wordplay.
'empty' suggests removing the centre.
'next to' means one lot of letters go next to another.
'fiat' becomes 'rule' (fiat can mean a rule or decree).
'coupe' with its centre taken out is 'ce'.
'ce'+'rule'+'an'='CERULEAN'
(Other definitions for cerulean that I've seen before include "Deep blue colour" , "Sky-blue in literary way" , "Sky-blue for Laurence" , "Light shade of blue" , "Azure" .)